What causes a SPN 7420 code?

SPN 7420 can be triggered by several issues — see the verified probable causes and step-by-step diagnostics shared by mechanics and owners on OBDIY.

Can I drive with a SPN 7420 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 7420 active.

How do I fix SPN 7420?

Follow the step-by-step diagnostic on this page, then read the verified fixes contributed by other Heavy Truck owners — the answer marked "Verified Cause" worked for the original poster.

J1939 SPN

SPN 7420

Cummins fault code 7420

What it means

Aftertreatment 1 Particulate Sensor - Data Valid But Above Normal Operating Range - Least Severe Level. This indicates the PM (Particulate Matter) sensor is detecting soot levels or electrical resistance values outside of normal parameters, often related to the sensor's internal heater or soot accumulation.